Anyone who examines the human eye carefully and investigates how we see has to be impressed with the incredible design of the eye. Many people fail to realize that the light that the eye sees is also an incredibly designed physical creation. Just explaining what light is and how it can have both wave properties and particle properties fills a lot of pages in most physics books. Light has frequency which lets it do things waves do such as diffraction and interference. It also has mass when it travels which disappears when it stops, allowing light to produce electricity from certain crystals and travel through a vacuum.

The thing that is miraculous about light is that it has all of these properties which allow it to do things that would not seem possible to most of us. Photons of light have different energies which allow light to do different things. The different colors that we see are because light has different energies--red light being lower energy than blue. Our eyes have special structures called cones which allow us to see colors--something most animals do not possess (just birds, some insects, and apes). The beauty of our world can be seen because of the different energies of light that surround us. The rainbow is caused by different energies of light interacting in different ways with drops of water in the atmosphere.

Our eyes only see a very small percentage of the light that is around us. Radio waves have a much lower energy than what our eyes see. The lower energy means that radio waves can pass through things like the walls of our homes which visible light cannot do. This means that we can turn on a radio inside our home and receive the radio waves that operate our televisions and radios. Microwaves are also light--again outside of our ability to see. These waves can cause water molecules to pick up energy without changing anything else in the material the water is in, and this allows us to cook our food. X-rays are higher in energy than what our eyes can see, and their energy allows them to pass through our bodies and show things we cannot see with our naked eyes alone. Gamma rays are even higher energy than X-rays and can be used to treat cancer and make measurements. Infra-red heats us, ultraviolet tans us, and special very long waves can be used for communications.
If our eyes could receive all of the light around us, it would do little
good to close our eyes. Even with our eyes closed, we would see a jumble
of light waves, including radio, TV, X-rays, microwaves, etc. Some
animals can see in these other parts of the light spectrum. Rattlesnakes
can see in the infrared so, on a totally dark night, the snake can see a
rat because of the heat which the rat's body emits. The way animals use
light is incredible, but it is even more remarkable to consider the nature
of light itself and what it has to be like to allow all of these uses to be
made. When the Creator said, "Let there be light," there was a
statement of the start of a truly remarkable creation which sustains the
entire physical cosmos in which we live.

(This subject is available in one of our children's books Why Is the Sky Blue?
Why Are Trees Green? $2.00 ppd.).